FDA staff appear to support Biogen’s ALS drug despite limited data

pharmafile | March 21, 2023 | News story | Medical Communications  

It appears that the FDA is inclined to support Biogen’s amyotrophic lateral sclerosis (ALS) drug, tofersen, with documents released on Monday stressing the need for “regulatory flexibility” when assessing treatments for life threatening diseases such as ALS. The agency does, however, recognise the lack of clinical trial evidence in this case.

Reviewers at the FDA have expressed concern over Biogen’s lack of plans to conduct follow-up testing which would confirm the efficacy of the drug ‒ this raises queries about whether Biogen are able to meet all of the FDA’s regulatory requirements should the agency give tofersen a conditional approval.

The drug was developed to treat patients with a genetic form of ALS, meaning they have mutations in a gene known as SOD1. However, mutations of the SOD1 gene account for a small proportion of all ALS cases, with only around 500 of the 30,000 ALS cases in the US linked to SOD1 mutations. This causes problems for Biogen and the FDA, as an accelerated approval would require additional clinical testing, however this could be difficult given the small population of patients.

FDA staff released briefing documents on Monday, which read: “Given the extremely rare nature of SOD1-ALS, and the very small pool of patients available for enrollment into a clinical study,” undertaking another adequate trial for tofersen in symptomatic patients with this form of the disease “does not appear to be feasible at this time.”


Betsy Goodfellow

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